A coextrusion feedblock can be used to bring together molten streams of thermoplastic materials from multiple extruders. Individual streams from different extruders can be brought together in the coextrusion feedblock to form a particular layer structure. The resulting multi-layer extrudate flow can then be delivered to a subsequent extrusion die, or another downstream tool, to produce the desired multiple layer extrudate.
In the case of a coextrusion feedblock adapted for producing 3-layer structures, the feedblock may initially be set-up for producing an A/B/C layer structure. If the operator later wishes to produce an A/C/B layer structure, for example, then with conventional feedblocks, it is first necessary to shut down the line and replace components, such as flow inserts, diverters, plugs, flow spools, and/or selector plates. Significant downtime results from replacing such parts and restringing the line for the new layer structure. This downtime can be on the order of hours.
It would be desirable to provide a coextrusion device that can be readily configured to produce different layer structures. It would be particularly desirable to provide a device that can be reconfigured without having to shut down the extruder(s), disassemble the device, or both. It would also be particularly desirable to provide a device that has reliable dynamic sealing when adjusted from one configuration to the next.